Anterior mediastinal tumor as a solitary lymph node metastasis of occult thyroid carcinoma

Solitary metastasis of occult thyroid carcinoma to the anterior mediastinum is very rare. A 65-year-old woman was examined for anterior mediastinal tumor based on the FDG accumulation on PET. We resected the tumor by video-assisted thoracic surgery. A pathological examination revealed that the tumor was lymph node metastasis of papillary thyroid carcinoma. The postoperative examination showed that the tumor was a solitary lymph node metastasis of occult thyroid carcinoma. Primary thyroid carcinoma has not appeared in 2 years since the surgery, and careful follow-up has been continued.